Left picture: The radiological diagnosis is a parietal epidermoid cyst completely lying in the skull. This characteristic finding is often detected incidentally on a skull x-ray which has been performed for other reasons. The defect is round at the beginning, becomes gradually larger and sometimes somewhat longitudinal-oval.
Right picture: In this patient an eosinophilic granuloma is present; the short history tells about a soft tissue mass of the skull which is painful on palpation. The osseous defect in the skull x-ray may display limits like a map and is multiple in case of another type of histiocytosis.

In both cases a defect of the skull is present.
Left picture: In this pathology the defect has sharp limits and a sclerotic border.
Right picture: In this radiological local finding a sclerotic border is missing, the limits are not round, and the borders are poorly defined.